1. Field of the Invention
The present invention relates generally to continuous measurement of optical fiber, and particularly to continuous attenuation measurement of optical fiber, including continuous measurement of attenuation from bending (“macrobend loss”).
2. Technical Background
Methods for measuring various properties of optical fiber often involve testing relatively short samples of stationary optical fiber. For example, methods for measuring light attenuation from bending (“macrobend loss”) typically involve winding a short length of fiber a specified number of turns around a mandrel of a specific diameter or deploying the fiber through a series of guide grooves to hold the fiber at a specific bend radius. Bend sensitivity is determined by comparing spectral power of the fiber in the bend condition to spectral power through the fiber without a bend.
Such methods can be tedious and time consuming. Moreover, in the case of testing for resistance to macrobend loss, they can fail, as a practical matter, to simultaneously take into account multiple factors that can lead to an unacceptable level of macrobend loss. Such factors can include, for example, variations in manufacturing processes, variations as a result of optical fiber nonuniformity, variations in the manner in which optical fiber can be bent, and the unpredictability as to which sections of optical fiber may be ultimately bent in application. Such variations can lead to an unacceptable level of signal loss, even if only a very small percentage of an entire length of optical fiber is affected. Thus, it would be desirable to provide a method that can quickly and efficiently measure resistance to macrobend loss along an entire length of optical fiber.